Tomatoes are continuously fruiting plants as well.
Like I said before,
nutrients don't need to be expensive to be good. Some
nutrient manufactures intentionally overprice their products. Many also create all kinds of additives for you to buy to get more of your money. A complete balanced nutrient doesn't need additives. If you do use an additive, there should be a good specific reason too. The 100% water soluble mineral salts that make up the nutrients are actually cheap, but some manufactures and retailers want to get as much of your money as they can. Another reason that many nutrient manufactures sell their products with such high profit margins is because most of their customers (80%-90%) are pot growers. Pot growers aren't concerned with nutrient costs because their own profit margins are so high as well. So as long as pot growers are willing to spend the money, there's no reason for them to lower their prices. But unlike pot growers, tomato growers don't get $1,000 per pound for their tomatoes.
The two most cost effective nutrients I know of are made by
Verti-Gro, and
Jr-Peters.
Even the smaller (only 4lb's each of nutrient and calcium nitrate) combo-pack from Verti-Gro breaks down to about $0.09 cents per gallon of nutrient solution even after the shipping costs, and make 500 gallons. But the 25lb quantities are a much better value breaking down to less than $0.02 cents per gallon (again including shipping costs), and making about 5,000 gallons.
Jr-Peters have similar value and quantities. Some need calcium magnesium, and others don't. I'd recommend calling them and telling them what your growing, and what they recommend. They don't list how many gallons they make online, but a 25 lb quantity makes something like 3,200 to 4,700. I've got the herb formula and including shipping (back then) only cost me about $67 for the 25'b bag. Even at 3,200 gallons that breaks down to $0.02 cents per gallon. Prices might be a little higher now (that was 2 years ago), but similar.
With Jr-Peters you will need to buy a small accurate kitchen scale because they don't use teaspoons etc. to measure it out. They go by weight. Something like 8.44 oz per 100 gallons of water, to 12.6 oz per 100 gallons of water for full strength nutrients (at least for the herb formula). To make less, it's just a little mathematics. But you need a good accurate digital scale to weigh it out with.
I've got to update some of the links, but I try to add any cost effective nutrients I come across to my list when I find them to share with others growers.
Cost effective hydroponic nutrients list